ESPN's Chris Forsberg reports that while Hayward is out of the boot, it'll be a test over the next week or so to see how his ankle reacts to the change as to whether or not it stays off:

Celtics forward Gordon Hayward did indeed get out of his waking boot today. No guarantee he stays out, depending on how his foot reacts, but he’s hopeful he’s done with it. Said Hayward: “Today has been awesome without the boot.”